x̄ =∑fx∑f=3= \frac{\sum fx}{\sum f} = 3=∑f∑fx=3
=(1×2)+(2×k)+(3×1)+(4×1)+(5×2)2+k+1+1+2=3= \frac{(1 \times 2) + (2 \times k) + (3 \times 1) + (4 \times 1) + (5 \times 2)}{2 + k + 1 + 1 + 2} = 3=2+k+1+1+2(1×2)+(2×k)+(3×1)+(4×1)+(5×2)=3
=2+2k+3+4+106+k=3= \frac{2 + 2k + 3 + 4 + 10}{6 + k} = 3=6+k2+2k+3+4+10=3
=19+2k6+k=3= \frac{19 + 2k}{6 + k} = 3=6+k19+2k=3
=19+2k6+k=31= \frac{19 + 2k}{6 + k} = \frac{3}{1}=6+k19+2k=13
=19+2k=3(6+k)
=19+2k=18+3k
=2k-3k=18-19
=-k=-1
∴k=1
